Mirror device

Abstract

In a biaxial mirror device where beams for connecting a first movable frame to a second movable frame and the second movable frame to a fixed frame pass a center of the mirror along an axis, an actuator for moving the second movable frame is composed of two first and second actuators and in a state that rotational angles of the movable frames are zero, the first actuator permits the second movable frame to start rotation and when it reaches a specific rotational angle, the second actuator permits the second movable frame to rotate, thus a large deflection angle is obtained even by the dissonance drive.

1 . A mirror device comprising:
 a mirror for scanning a laser beam on a face as a screen and projecting an image;   a first movable frame with said mirror attached to;   a second movable frame connected to said first movable frame via a first beam; and   a fixed frame connected to said second movable frame via a second beam; wherein:   comb teeth formed in said first movable frame and comb teeth formed in said second movable frame are combined, and a first electrostatic actuator is formed by combination of said comb teeth formed in said second movable frame with comb teeth formed in said fixed frame,   a second electrostatic actuator composed of inclined electrodes is installed under said first movable frame and said second movable frame, and   said mirror is operated horizontally and vertically by said first and second actuators.   
     
     
         2 . The mirror device according to  claim 1 , wherein:
 said mirror rotates biaxially by said first beam and said second beam.   
     
     
         3 . The mirror device according to  claim 1 , wherein:
 said second movable frame and said first electrostatic actuator support a parallel flat plate type electrostatic actuator with an elastic cantilever beam and   said parallel flat plate type electrostatic actuator operates, thus said cantilever beam changes elastically, and said second frame is structured so as to be inclined by a rotary motion on an axis of said second beam, and   said inclined electrodes of said second electrostatic actuator are formed so as to obtain an almost same inclination as a maximum inclination when said second movable frame more inclines and approaches by an operation of said second electrostatic actuator.   
     
     
         4 . The mirror device according to  claim 1 , wherein:
 said first actuator is a comb-tooth electrode type electrostatic actuator, and   positions in a height direction of said comb-tooth electrodes installed on a side of said second movable frame and said comb-tooth electrodes installed on a side of said fixed frame have an offset, and   after said second movable frame is rotated by electrostatic force when a voltage is applied between said comb-tooth electrodes and exceeds a predetermined rotational angle, force of said second electrostatic actuator using said inclined fixed electrodes increases, thus said mirror is rotated.   
     
     
         5 . The mirror device according to  claim 1 , wherein:
 said positions in said height direction of said comb-tooth electrodes installed on said side of said second movable frame and said comb-tooth electrodes installed on said side of said fixed frame have said offset and   an actuator for driving in a horizontal direction is an electrostatic actuator for rotating said first movable frame by said electrostatic force when said voltage is applied between said comb-tooth electrodes and is driven at a resonance frequency of a system with said first movable frame and said mirror united.   
     
     
         6 . The mirror device according to  claim 1 , wherein:
 said mirror and said first movable frame and second movable frame are hermetically sealed spatially with a cover where said second movable frame is joined to said fixed frame portion and   a pressure of said hermetically sealed space is 1,000 Pa or lower.